1. Field of this Invention
This invention relates to a process for the production of acetoacetic acids of the general formula R.sub.1 CH.sub.2 --CO--CR.sub.2 R.sub.3 --COOH, wherein R.sub.1 represents bromine or chlorine and R.sub.2 and R.sub.3 each represents hydrogen, bromine or chlorine.
2. Prior Art
It is known that acetoacetic acid can be prepared by carefully hydrolysing acetoacetic esters with dilute aqueous potassium hydroxide solution at room temperature. In this reaction, the acid formed has to be separated off from any unreacted ester by conversion into its barium salt, and the free acid has to be liberated again from this salt. The free acetoacetic acid obtained in this way is described in the literature as a viscous liquid which cannot be further purified on account of its tendency to decompose into acetone and carbon dioxide.
It is also known that .gamma.-chloro-acetoacetic acid can be prepared by the acid hydrolysis of .gamma.-chloro-acetoacetic ester. The hydrolysis reaction, which is carried out over a period of 45 hours at room temperature with 2 N hydrochloric acid, gives a yield of 46 percent. There is no evidence of the preparation of any other acetoacetic acids in free form.
Attention is directed to U.S. Pat. No. 2,209,683; Roberts et al., "Basic Principles of Organic Chemistry", W. A. Benjamin, Inc., (1964), pp. 530-31; Noller, Carl R., "Chemistry of Organic Compounds," W. B. Saunders Co., (1951), p. 756 Kirk-Othmer, "Encyclopedia of Chemical Technology," 1st Ed., Vol. 1, pp. 143 & 153; Boese, A. B., Ind. Eng. Chem., Vol. 32, (1940), pp. 16-22; and Chick, F., et al., J. Chem. Soc., Vol. 97, (1910), pp. 1980 & 1990.